It is known to use a concentric camshaft phaser (two cam shafts, one radially inside the other) to control an intake or exhaust valve train for an internal combustion engine. It also is known to use a control gear on the camshaft phaser to drive a second gear or gear driven phaser for the intake or exhaust valve train. For proper timing and operation of the phasers, the radial runout of the control gear (circumferential position of the control gear with respect to the cam shafts) must be precisely controlled. The prior art teaches the use of intermediate components, such as fasteners, to secure the control gear to the camshafts. However, the use of intermediate components introduces tolerance variations associated with the components that add an additional degree of error to the runout of the control gear. The introduced tolerances can result in a less precise circumferential location of the control gear with respect to the camshaft, adversely impacting gear durability, and timing of a system using the phaser. In addition, during operation of the phaser, gear loads are indirectly transferred to the camshafts via the phaser, resulting in unreliable radial transfer of the gear loads. Thus, it is difficult to maintain the necessary gear radial runout for reliable, durable, and repeatable operation of the phasers.